In various industries, protective clothing is becoming of increasing importance to workers and their employers to address concerns of health, safety and cleanliness. While these concerns may change in emphasis from industry to industry, workers must be effectively protected from exposure to contaminants such as asbestos and other fibrous materials, particulate matter and liquids such as water and oil. However, while effective protection must be provided, such clothing must also provide the worker with an acceptable level of comfort (i.e., breathability). This feature is especially significant for workers who encounter extreme or varying temperatures, humidity conditions, etc.
Therefore, much effort has been directed toward the development of protective clothing which will provide workers with good levels (i.e., acceptable levels) of protection and comfort. The development of such clothing is a difficult task because protection can naturally lead to impenetrability which, in turn, tends to decrease comfort. This lack of comfort is or may be caused by the inability of the clothing to breathe.
Air permeability (i.e., porosity) is an important factor in the performance of fabrics such as those used to make protective clothing. Air permeability also provides an indication of the "breathability" of weatherproof and rainproof fabrics and of coated fabrics in general. Manufacturing processes can have an appreciable effect on porosity by causing changes in the length of air flow paths through the fabric. For example, hot calendering during the manufacturing process will flatten the fibers and reduce air permeability.
Other factors which must be addressed in the manufacture of protective clothing include bulk and barrier properties.
The prior art has attempted to address the above-described need for comfortable and protective clothing. For example, U.S. Pat. No. 4,823,404 describes a protective garment having separate top and bottom parts, in which the front of each part is made from a nonwoven fabric having a smooth calendered outer surface and an uncalendered inner surface and in which the back of each part is made from a breathable material. Additionally, U.S. Pat. No. 3,971,373 describes a porous sheet product which comprises a web of melt-blown microfibers and a three-dimensional arrangement of particles. Further, coassigned U.S. Pat. No. 5,165,979 describes a three-dimensional nonwoven web of drawn thermoplastic fibers formed from a blend of polypropylene and polybutylene and the combination of such a web with various layers in laminate form especially useful for wiper applications.
However, for various reasons, the prior art has not fully met the need for comfortable protective clothing which has both good barrier properties and good air permeability. Therefore, a need exists for such clothing.